Eyelet for reinforcing the edge of a hole in a carrier strip and device for attaching an eyelet to a carrier strip

ABSTRACT

The invention relates to a ringless eyelet ( 10′ ) comprising a plate ( 11 ) arranged on the display side ( 23 ) of the carrier strip ( 20 ), and a tube-shaped collar penetrating the hole in the carrier strip. The hem of the collar of the eyelet element ( 10′ ) is supported on the rear side ( 24 ) of the carrier strip ( 20 ). The aim of the invention is to connect the eyelet to the carrier strip ( 20 ) faster and in a more cost-effective manner. In order to achieve this, the free end part of the collar of the eyelet element ( 10′ ) is provided with projections ( 16 ). An essentially closed ring profile ( 50 ), into which the collar projections ( 16 ) are integrated, is created when the collar is hemmed. After hemming, pressure points ( 40 ) are created on the carrier strip ( 20 ) between the collar projections ( 16 ) and the abutment surfaces ( 49 ) formed by the plate ( 11 ), said pressure points reliably holding the carrier strip ( 20 ). Said carrier strip ( 20 ) extends namely inside ( 51 ) the ring profile ( 50 ) beyond the pressure points ( 40 ). An eyelet is obtained using only one

[0001] The invention pertains first to an eyelet of the type indicatedin the introductory clause of claim 1. There are two-part eyelets, thefirst part of which consists of an eyelet, the second consisting of adisk. These two parts are located on opposite sides of the carrier weband clamp the carrier web between them in sandwich-like fashion.

[0002] One-part eyelets are also known, however, which do not have adisk part and which thus consist only of an eyelet part (U.S. Pat. No.2,107,375 A). Pleats are formed in the end of the neck of the eyeletpart, as a result of which radial expansions are created between axialprojections. When the eyelet part is flanged over, a C-shaped profile isformed between the neck and the plate, the radial expansions beingsupported against the rear surface of the carrier web. The carrier webthus extends radially into the interior of the C-shaped profile. Thisknown eyelet has limited resistance to pull-out.

[0003] The invention is based, first, on the task of developing aninexpensive, quickly installable eyelet of the type indicated in theintroductory clause of claim 1, which, after it has been attached to thecarrier web, is characterized by high resistance to tear-out. This isachieved according to the invention by the measures cited in claim 1, towhich the following meaning attaches:

[0004] In the invention, a closed, ring-shaped profile is formed whenthe neck is flanged over; the projections provided at the end of theneck are included inside this profile. As a result, special compressionpoints, which provide very high resistance to the tensile stressesexerted on the carrier web, are produced on the gripped carrier webinside the ring-shaped profile. These compression points are formedbecause the projections on the ring-shaped, flanged-over neck press anarea of the carrier web surrounding the hole against opposite supportsurfaces, which, in the case of the present ring-shaped profile, areformed by the plate or by the transition between the plate and the neckof the eyelet part. The carrier web extends beyond the compressionpoints to the edge of the hole in the interior of the ring-shapedprofile. Stresses acting on the carrier web actually improve the grip atthe compression points where the material around the edge of the hole inthe web has been rolled up into the interior of the ring-shaped profile.The eyelet according to the invention is much more resistant to pull-outthan the state of the art indicated above.

[0005] In comparison with the much more complicated, two-part eyelets,the eyelet according to the invention provides a surprisingly highresistance to tear-out; it is, in fact, 30-75% stronger. This strengthis obtained precisely in the case of the previously so difficult tohandle flexible or stretchable carrier webs, which could not beprocessed at all with one-part eyelets in the past. Because of theone-piece design of the invention, the disk part is eliminated, whichsaves material, warehouse costs, freight costs, and handling during theinstallation process. Because the one-part eyelet part according to theinvention can be installed rapidly, the cost of installing the eyelet isreduced. The neck of the eyelet part according to the invention must belong enough to make it possible for the desired ring-shaped profile tobe obtained during the flanging operation. The thickness of the carrierweb, of course, must also be taken into account. The only other step tobe taken is to produce the axial or radial projections at the free endof the neck, which can be done in various ways.

[0006] One possibility is to form the projections by making radial holesin the tubular wall of the neck. When the neck is flanged over, theseradial projections penetrate into the edge area of the material aroundthe hole in the carrier web being gripped, where they dig themselves inand produce the compression points against the opposing support surfaceon the plate. The other possibility, namely, forming projections whichproceed in the axial direction, is easier to manufacture, however. Thepronged or wave-like terminal edge of the neck mentioned for thispurpose in claim 2 is suitable. In this case, the entire edge of theneck has a continuous profile and does not, as in the state of the artmentioned above, show individual projections spaced a certain distanceapart. When the ring-shaped profile is formed, both the neck and itsprojections are deformed jointly according to the invention. When thering-shaped profile is produced during the flanging-over operation, theprong digs into the web material, and there is therefore not just aclamping effect between the prong and the opposing support surface ofthe plate but also a positive connection, which is established betweenthe prong and the carrier web. The greater the tensile force exerted onthe carrier web, the greater the strength with which the prongs dig intothe web. This explains the surprisingly high resistance of the eyeletaccording to the invention to tear-out.

[0007] The invention also pertains to a device for installing the eyeletaccording to the invention. In the case of the known device (U.S. Pat.No. 1,838,973 A), which is intended for two-part eyelets, the thrustring in the lower tool projects beyond the cutting edge provided here.The upper tool has an axially movable, central insert with a bore; thisinsert projects out axially beyond the adjacent surfaces of the uppertool. During the working stroke of the two tools, the carrier web ispushed by the central insert of the upper tool into the thrust ringbefore the central insert meets the cutting edge of the lower tool tocut the hole in the carrier web. The attachment of the carrier web tothis two-part eyelet, which consists of both an eyelet part and thepreviously mentioned disk part, is therefore unattractive, because foldsare formed in the carrier web.

[0008] The invention is therefore also based on the task of developing adevice which can be used to attach the one-part eyelet cited in claim 1more attractively to the carrier web and with greater resistance totear-out. This is accomplished according to the invention by thefeatures cited in the characterizing clause of claim 9, to which thefollowing special meaning attaches:

[0009] In the invention, the upper tool is provided with acounter-thrust thrust ring to work together with the thrust ring in thelower tool, the counter-thrust ring being subjected to a force actingtoward the lower tool. It is recommended here, in accordance with claim10, that these two rings be provided with opposing beveled surfaces.When the two tools perform their stroke, the carrier web is tensionedbetween the two rings, and the beveled surfaces exert an additionalstretching and smoothing-out effect on the carrier web. During thefollowing flanging operation of the one-part eyelet, the carrier web iskept flat and smooth, which ensures that the eyelet is attached ideallyto the carrier web. The tensioning of the web minimizes the amount ofmaterial which is pulled into the eyelet. This has the result thatspacing of the eyelets can be maintained with precision, and positionaldeviations can be limited even in the case of large tarps.

[0010] Additional measures and advantages of the invention can bederived from the subclaims, from the following description, and from thedrawings. The drawings illustrate the invention on the basis of anexemplary embodiment:

[0011]FIGS. 1 and 2 show top views of the visible side and the rearsurface, respectively, of a carrier web equipped with an eyeletaccording to the invention;

[0012]FIG. 3 shows a greatly enlarged cross section through theinstalled eyelet according to FIG. 1 along the cross-sectional lineIII-III in FIG. 1;

[0013]FIG. 4 shows an axial cross section through the special eyeletpart of the diskless eyelet according to the invention in the originalstate, that is, before it has been installed in the carrier web;

[0014]FIG. 5 shows an enlarged, flattened view of part of the edge areaof the eyelet part according to the invention, namely, the areaindicated by the “V” in FIG. 4; and

[0015]FIG. 6 shows an axial half-cross section of the parts of atwo-part device according to the invention for installing the eyeletpart shown in FIG. 4, the upper tool being at the top end of its strokewith respect to the lower tool.

[0016] As FIGS. 1 and 2 show, an eyelet is to be used to reinforce theedge area 21 around a hole 22, which has been cut in a carrier web 20.The carrier web 20 is usually a flexible and possibly stretchablematerial such as an automobile tarp. According to the invention, thehole is reinforced with a one-piece eyelet part 10. In FIGS. 4 and 5,the eyelet part 10 is shown in its original state, before installation.FIGS. 1, 2, and 3, however, show the eyelet part 10′ after installation,in its final state in which it is exercising its hole-reinforcingfunction. As FIGS. 1 and 2 show, an eyelet is to be used to reinforcethe edge area 21 around a hole 22, which has been cut in a carrier web20. The carrier web 20 is usually a flexible and possibly stretchablematerial such as an automobile tarp. According to the invention, thehole is reinforced with a one-piece eyelet part 10. In FIGS. 4 and 5,the eyelet part 10 is shown in its original state, before installation.FIGS. 1, 2, and 3, however, show the eyelet part 10′ after installation,in its final state in which it is exercising its hole-reinforcingfunction.

[0017] The eyelet part 10 can be divided into a plate 11 with a curvedcross section, extending essentially in the radial direction, and atubular neck 12, extending in the axial direction. To increase thedimensional stability of the eyelet and to make it easier to flange overthe neck 12 into a ring, as will be described in greater detail below,the plate 11 is provided with a curved profile 13. As a result, anespecially conspicuous arc-shaped transition 14 is obtained between theplate 11 and the neck 12. The neck is provided at its free end 15 withaxial projections 16, which, therefore, extend in the direction of theneck 12. These projections consist in the present case of a curved,pronged terminal edge 17, as can be seen in FIG. 5. This edge has thefollowing appearance.

[0018] The tips 17 of the prongs are provided with convexly roundedareas 27, whereas the gaps 18 between the prongs have concavely roundedareas 28. As a result, the pronged profile 19 acquires a wave-like form.The course of the waves is asymmetric. That is, the radius of curvatureof the rounded areas 27 of the prong tips 17 is smaller than that of therounded areas 28 of the gaps between the prongs.

[0019] This eyelet part 17 is attached to the carrier web 20 by thedevice 30, shown in FIG. 6. The device 30 consists of essentially fiveparts, which are able to move in the axial direction with respect toeach other in a chronological sequence. These parts include, first, thebottom tool 32, which, in the present case, remains at rest and whichcarries a thrust ring 34, which is able to move passively in the axialdirection with respect to the lower tool. In addition, the device 30also includes an upper tool 31, which is able to move actively withrespect to the lower tool 32 and which has a central, coaxial insert 33.This insert is also able to move passively in the axial direction withrespect to the upper tool 31. Finally, the upper tool 31 is enclosedcircumferentially by a counter-thrust ring 54, which is also able tomove passively in the axial direction. The central insert 33 and thecounter-thrust ring 54 are subjected to load in the direction of theforce arrows 35 and 55 toward the lower tool 32, whereas the thrust ring34 in the lower tool 32, in mirror-image fashion, is acted upon by agroup of springs 56 acting in the direction of the force arrow 36 towardthe upper tool 31, these springs being installed in axial holes in thebottom tool 32. The springs 56 are designed as helical springs, and pins57 seated on the thrust ring 34 fit into the interior of the helicalturns. The tool assembly 31, 33, 54 on the one side and the toolassembly 32, 34 on the other are able to move up and down with respectto each other, as indicated by the motion arrow 37 of the upper toolassembly 31, 33, 54.

[0020] The counter-thrust ring 54 is guided on the circumferentialsurface 63 of the upper tool 31. The force 55 exerted by thecounter-thrust ring 54 is produced by a compression spring 64, which issupported between a flank of a circumferential flange 65 on the uppertool 31 and the contact surface of a cutaway portion 66 of thecounter-thrust ring 54. The extent to which the counter-thrust ring 54extends outward is determined by end stops. These consist in the presentcase of the heads 67 of a group of guide rods 68, the length of whichcan be adjusted by the use of a threaded section 69 and a lock nut 71.When in the resting state, the head 67 of the rod is supported on thetop surface of the flange 65. As a result, the desired extension 70 ofthe counter-thrust ring 54 relative to the upper tool 31 is determined.

[0021]FIG. 6, as already mentioned, shows the device at the upperreversal point of its stroke 37, at which the maximum distance 38 ispresent between the upper tool 31 and the lower tool 32. As a result, aneyelet part 10 can be conveniently inserted into the receiving profileof the upper tool 31 and around the central insert 33. For this purpose,the upper tool 31 has a receptacle 39, which conforms to the profile ofthe plate 11. The area provided with the receptacle 39 is subject towear during normal use. To facilitate the renewal of a worn-out device30, therefore, the lower part of the upper tool is provided with aninsert 31′, which is detachably connected to the upper part of the uppertool 31 by suitable means such as the screw shown in the drawing or thelike. This insert 31′ carries the receptacle 39.

[0022] After the eyelet part 10 has been inserted, the end of the neck20 is supported on the circumferential surface of the central insert 33.The central insert 33 is provided with a flat end surface 43. To securethe eyelet part in position in the tools 31, 33, a retaining element 44,which, in the present case, consists of a radially spring-loaded pin, isused, which is located in the circumferential area of the central insert33.

[0023] The carrier web 20 is laid between the two tool parts 31, 32; atthis point, the web is still unperforated. The previously mentionedsprings 56 hold the thrust ring 34 in a defined starting position, shownin FIG. 6. At maximum stroke of the tool, the defining-upper surface 45of the thrust ring 34 is located above or preferably at the same levelas a cutting edge 42 provided on the cutting tool 32. As a result, ahorizontal support plane 60 for the carrier web 20, illustrated inbroken line in FIG. 6, is created at the thrust ring 34.

[0024] During the downstroke 37 of the upper tool assembly 31, 33, 54,the leading counter-thrust ring 54 makes contact first with the carrierweb 20 lying on top of the thrust ring 34. The two rings 34, 54 areprovided with bevels 58, 59, which are essentially parallel to eachother and which grip the carrier web 20 between them, as a result ofwhich the carrier web 20 is initially put under a certain amount oftension. The bevel 58 of the thrust ring 34 forms an acute angle 61 tothe support plane 60, shown in dash-dot line in FIG. 6, which plane isdetermined by the end surface 45 of the thrust ring 34 serving tosupport the carrier web 20. The counter-thrust surface 59 of the thrustring 54 just mentioned is essentially parallel to the thrust surface 58.When the two tools 31, 32 are moved toward each other 37, therefore, thecarrier web 20 is pulled over the edge 62, which is formed between theend surface 45 and the bevel 58 of the thrust ring 34. As a result, thecarrier web is drawn flat in the area 29 to be punched. The carrier web20 thus assumes a stretched-out condition in the support plane 60mentioned.

[0025] Then the central insert 33, under the force being exerted by thepress plunger, makes contact with the upward-facing, visible side 23 ofthe carrier web 20, thus pressing it against the cutting edge 42 of thelower tool 32, which is resting against the bottom surface 24 of thecarrier web. As a result, a circular hole is punched out of the carrierweb 20. The radius 46 of the hole determined by the cutting edge 42 issmaller than the radius 26 of the neck 12 of the eyelet indicated at 26in FIG. 6.

[0026] When the upper tool 31 is lowered further in the direction of thestroke arrow 37, the carrier web 20 is pulled even tighter between twobevels 58, 59 of the two rings 34, 54. The neck 12 of the eyelet part 10continues to pass through the hole thus formed and into the lower tooluntil the plate 11 of the eyelet part 10 arrives at the thrust ring 34,the carrier web 20 ending up between the plate and the ring. During thisdownward movement 37, the upper tool 31 overcomes the elastic force 36being exerted from underneath by the thrust ring 34, and the neck 12 ofthe eyelet and its axial projections 16 are flanged over against theflanging profile 47 of the lower tool 32. The elastic force 54 of thethrust ring 34 acting from above is weaker than the ejection force 36acting from below on the thrust ring 34. As in the case of the uppertool 31, the lower tool 32 also has an insert 32′, positioned in theaxial area, which carries the defining flanging-over profile 47. Thisflanging-over profile 47 wears out after prolonged use. At that point,it necessary merely to replace this insert 32′.

[0027] During the flanging operation, the special riveting relationshipsshown in FIG. 3 are obtained. Practically the entire length 48 of theneck of the eyelet part shown in FIG. 4 is rolled up into a ring-shapedprofile 50, shown in FIG. 3, on the rear surface 24 of the carrier web20. The neck projections 16 are rolled up inside this ring-shapedformation 50. These neck projections 16 are pressed against an opposingsupport surface 49, provided by the previously described curved section13 of the plate 11; the previously mentioned area 21 of the carrier web20 situated around the edge of the hole as indicated in FIG. 6 ends upbetween the projections and the opposing support. As a result, thecompression points 40, which proceed around the plate in a ring-likemanner, are obtained, as can be seen in FIG. 3. The end part 41 of thecarrier web 20 continues into the interior 51 of the ring-shapedprofile, conforming to the profile 50 and thus acquiring the form of asegment of a ring. The bevels 58, 59 continue to hold the carrier webfirmly in place while the end part 41 is being rolled up during theriveting process.

[0028] When the eyelet part installed on the carrier web 20 is properlyused, the tensile forces indicated by the force arrows 52 in FIGS. 1-3will occur. These tensile stresses 52 are absorbed at the compressionpoints 40. First, a clamping action between the neck projections 16 andthe opposing support surface 49 is present at the compression points 40.There is also a positive interconnection because of the profiling 19 ofthese projections 16, as described above. That is, the tips 17 of theprongs dig into the web material, but, because of the rounded areas 27,28 of the pronged edge 19, the web 20 is not torn. A notch effect isthus avoided. On the other side of these compression points 40, asdesignated at 53 in FIG. 3, the web becomes thicker again in front ofthe prong tips and also in the curved gaps 18 between the prongs. Thatis, the web 40 tries to return to its original thickness 25 at 53. Underthe tensile stresses 52 on the web 20, the wave-like edges of the neckprojections 16 dig into these step-like areas of increased thickness 53of the web material 20. The positive interlocking is thus improved evenmore, and the eyelet part 10′ riveted into the web 20 thus acquires asurprisingly high degree of tensile strength.

List of Reference Numbers

[0029]10 eyelet part (original state, FIG. 4)

[0030]10′ riveted state of 10 (FIGS. 1-3)

[0031]11 plate of 10

[0032]12 neck of 10, eyelet neck

[0033]13 curved profile of 11

[0034]14 arc-shaped transition between 11 and 12

[0035]15 end part of 12

[0036]16 axial projection of the neck at 15 (FIG. 4)

[0037]17 tip of prong (FIG. 5)

[0038]18 gap between prongs

[0039]19 pronged edge at 15 (FIG. 5)

[0040]20 carrier web

[0041]21 area at edge of hole in 20

[0042]22 hole in 20

[0043]23 visible side of 20

[0044]24 rear surface of 20

[0045]25 web thickness of 20 (FIG. 6)

[0046]26 radius of neck 12 (FIG. 6)

[0047]27 convexly rounded area of 17 (FIG. 5)

[0048]28 concavely rounded area of 18 (FIG. 5)

[0049]29 hole punching from 20 (FIG. 6)

[0050]30 device

[0051]31 upper tool of 30

[0052]31′ replaceable insert in 31

[0053]32 lower tool of 30

[0054]32′ replaceable insert in 32

[0055]33 central insert in 31

[0056]34 thrust ring in 33

[0057]35 force arrow of 33

[0058]36 arrow of the elastic force of 34

[0059]37 stroke arrow of 31 with respect to 32 (FIG. 6)

[0060]38 maximum stroke between 31 and 32

[0061]39 receptacle in 31 for 11

[0062]40 compression point of 20 between 16 and 49 (FIG. 3)

[0063]41 end part of 20 on the other side of 40 (FIG. 3)

[0064]42 cutting edge of 32

[0065]43 flat end surface of 33 (FIG. 6)

[0066]44 retaining element for 10 at 33 (FIG. 6)

[0067]45 end surface for 20 on 34

[0068]46 radius of hole 29 (FIG. 6)

[0069]47 flanging profile of 32 (FIG. 6)

[0070]48 length of neck 12 (FIG. 4)

[0071]49 opposing support surface on 11 for 16 (FIG. 3)

[0072]50 ring-shaped profile of 12 at 10′ (FIG. 3)

[0073]51 interior of the ring-shaped profile of 50 (FIG. 4)

[0074]52 arrow of the tensile force on 20

[0075]53 step-like increase in the thickness of 20 behind 40 (FIG. 3)

[0076]54 counter-thrust ring

[0077]55 force of 54

[0078]56 spring for 36

[0079]57 pin on 34 for 56

[0080]58 bevel of 34, beveled surface

[0081]59 counter-bevel of 54, counter-beveled surface

[0082]60 support plane

[0083]61 angle of 58 with respect to 45

[0084]62 edge between 45 and 58 of 34

[0085]63 circumferential surface of 31

[0086]64 compression spring

[0087]65 flange

[0088]66 cutaway area

[0089]67 head of 68

[0090]68 guide rod

[0091]69 threaded engagement

[0092]70 extension

[0093]71 lock nut

1. Eyelet for reinforcing the area (21) around the edge of a hole (22)in a carrier web (20), with a diskless eyelet part (10, 10′), consistingof a plate (11), which rests on the visible side (23) of the carrier web(20); of a tubular neck (12), which passes through the hole (22); and ofan arc-shaped transition (14) between the plate (11) and the neck (12);where the free end part (15) of the neck (12) is provided withprojections (16), which extend in the axial and/or the radial direction;and where, after the riveting operation, a flanging of the neck (12) ofthe eyelet part (10′) is present on the rear surface (24) of the carrierweb (20), characterized in that the completed flanging of the neck (12)results in an essentially closed, ring-shaped profile (50), and theprojections (16) of the end part (15) of the neck (12) are included inthe ring thus formed; in that in the ring-shaped profile (50), theprojections (16) of the neck (12) press against an opposing supportsurface (49) formed by the plate (11) or by the transition area (14),the area (21) of the carrier web (20) around the edge of the hole endingup between the projections and the support surface, compression points(40) thus being produced on the gripped carrier web (20), as a result ofwhich a step-like increase (53) in the thickness of the web material isformed in front of the compression points; in that in the interior (51)of the ring-shaped profile, the end part (41) of the carrier web (20)extends beyond the compression points (40) to the edge of the hole andforms a segment of a ring conforming to the shape of the ring-shapedprofile (50); and in that when tensile stresses are exerted on thecarrier web, the projections (16) engage positively with the step-likeincrease (53) in the thickness of the web material and oppose thetensile forces.
 2. Eyelet according to claim 1, characterized in thatthe axial projections (16) on the neck consist of a pronged edge (19) atthe end of the neck (12).
 3. Eyelet according to claim 2, characterizedin that the tips (17) of the prongs are convexly rounded, in that thegaps (18) between the prongs are concavely rounded, and in that the tworounded areas (27, 28) define a wave-like course of the pronged edge(19).
 4. Eyelet according to claim 3, characterized in that the prongededge (19) is asymmetrically wave-like.
 5. Eyelet according to claim 3 orclaim 4, characterized in that the convexly rounded areas (27) of theprong tips (17) are smaller than the concavely rounded areas (28) of theprong gaps (18).
 6. Eyelet according to one of claims 1-5, characterizedin that the material of the carrier web (20) is flexible and/orstretchable.
 7. Eyelet according to claim 6, characterized in that thecarrier web (20) consists of a canvas tarp.
 8. Eyelet according to claim6, characterized in that the carrier web (20) consists of a reinforcedplastic sheet.
 9. Device (30) for installing eyelet parts (10) in acarrier web (20) according to one of claims 1-8, with a lower tool (32),which is equipped with the flanging-over profile (47) for the neck (12)of the eyelet part (10) and which also has a ring-shaped cutting edge(42); with an upper tool (31), which holds the eyelet part (10), canmove up and down (37) relative to the lower tool (32), and has a centralinsert (33), which is able to move in the axial direction against anelastic force (35); where the carrier web (20) is positioned between thetwo tools (31, 32), and the cutting edge (42) of the lower tool (32)works with the end surface (43) of the central insert (33) to exert ahole-cutting action (29) on the carrier web (20) situated between them;with a thrust ring (34) in the lower tool (32), which is located acertain radial distance away from the flanging profile (47) and issubjected to a force (36) directed toward the upper tool (31); where theradius (46) of the hole of the cutting edge (42) is smaller than theoutside radius (26) of the neck (12) of the eyelet part (10),characterized in that the end surface (43) of the central insert (33) isessentially flat and free of pretensioning pins which prestretch thecarrier web (20); in that at the point of maximum stroke between the twotools (31, 32), the thrust ring (34) is located essentially on the samelevel as the cutting edge (42) of the lower tool (32) and works togetherwith the cutting edge (42) to form a support plane (60) for the carrierweb (20) to be placed between the two tools (31, 32); in that acounter-thrust ring (54) in the upper tool (31) is associated with thethrust ring (34) and is subject to a force (55) directed toward thelower tool (32); and in that the carrier web (20) is tensioned betweenthe two rings (34, 54) during the stroke (37) of the tools.
 10. Deviceaccording to claim 9, characterized in that the two rings (34, 54) areprovided with opposing beveled surfaces (58, 59), which face each other,and which tension the carrier web (20) between them during the workingstroke of the tools (31, 32).
 11. Device according to claim 10,characterized in that the beveled surface (58) and the support plane(60) form an acute angle (61) pointing in the direction (37) of thestroke, the support plane being determined by the support surface (45)of the thrust ring (34); and in that the opposing beveled surface (59)of the counter-thrust ring (54) is essentially parallel to the beveledsurface (58) of the thrust ring (34).
 12. Device according to one ofclaims 9-11, characterized in that a helical compression spring has aring-shaped end surface, and in that this terminal ring-shaped surfaceforms the thrust ring (34), while the compression spring produces theforce (36).